An Iowa woman was charged with animal torture after she hanged a dog she shared with her boyfriend from a rafter in his garage.

Sheena Cornwell, 28, of Des Moines told police she hanged Lilly, a 15-year-old pit bull mix, by her collar and leash because she "was going to die soon anyway," the police report stated.

Cornwell did not leave the garage to return to the house until the dog was dead, her boyfriend, Joshua Vandyke, told police.

Sgt. Jason Halifax, a Des Moines Police Department spokesman, told ABCNews.com that Cornwell's boyfriend, Joshua Vandyke, came home from work around 5 p.m. on Saturday and found Cornwell upset about Lilly's behavior. Vandyke told police that Cornwell then took the dog into the garage.

According to the police report, Vandyke told police that Cornwell had been annoyed with Lilly for the past two months, because the dog paced back and forth in the house, but he was shocked that she would do this.

Halifax said that when police arrested Cornwell, she admitted to hanging the dog and said she didn't know what the big deal was. Vandyke had told police that Cornwell had a drinking problem and had been drinking vodka on Saturday, according to the police report.

"She's a nasty person," Halifax said.

Halifax said that the police animal control unit came to the house to unhook the dog from its leash and remove it from the house.

Sylvia White, who lives three doors down from Vandyke, told ABCNews.com that she stood on her front lawn when patrol cars arrived on her block Saturday evening. She said she did not know what happened until she saw animal rescue enter the house.

"[Animal control] came out and he was carrying what looked like a dog," she said. "All you could see was the back legs sticking up. He had it in a plastic bag and he carried it out."

The body of the dog was taken to Iowa State University for a necropsy today, Halifax said.

Cornwell was arrested and taken into custody at Polk County Jail on Saturday. She has since been released on bond.

Halifax said that Vandyke wanted to file a "no-contact" order against Cornwell to keep her from returning to his house when she got out of jail. He told police he feared for the safety of the couple's other two dogs.

The couple has been living together for the past two years in the house Vandyke owns, according to the police report.